1. Field of the Invention
The present invention generally relates to a probe unit for test tools and method of manufacturing the same, and more particularly, to a probe unit with low cost and simple tip replacement and method of manufacturing the same.
2. Description of the Prior Art
Scanning probe microscopes (SPMs) providing very high resolution images of various surface properties are typically employed as a means of measuring surface topography and corresponding electrical property analysis. Different types of electrical properties can be measured, such as conductivity, voltage, capacitance, resistivity, current, and others. Accordingly, many different SPM techniques may be used when measuring electrical properties. For example, SPM techniques that may be used for synchronously providing electrical signals corresponding to topographic images comprise scanning capacitance microscopy (SCM), scanning spreading resistance microscopy (SSRM), Kelvin force microscopy (KFM) and conductive atomic force microscopy (C-AFM).
The scanning capacitance microscope (SCM) apparatus works by scanning a tiny tip over the surface of a sample being imaged, while synchronously measuring the electrical properties of the sample. A typical SCM apparatus comprises an atomic force microscope (AFM) and an ultra-high frequency (UHF) resonant capacitance sensor can synchronously provide a two-dimensional image. The AFM acquires surface topographic images, and the UHF resonant capacitance sensor provides a synchronous two dimensional differential capacitance images. The AFM typically comprises a cantilever and a conductive probe at the free end of the cantilever. In most AFMs the position of the cantilever is detected with optical techniques. A red laser beam (670 nm) reflected off the back of the cantilever onto a position-sensitive photo-detector is adapted to detect the position of the cantilever. The AFM can thus generate topographic images.
However, photo/laser perturbations, such as the photovoltaic effect and the high-level carrier injection effect induced by stray light of the AFM red laser beam lead to distorted differential capacitance (dC/dV) profiles and hence perturb the contrast of SCM images. The photo/laser perturbations induced by the AFM laser beam not only affect the image contrast of SCM images, but also reduce the accuracy of the determination of the carrier concentration distribution.
In addition, the conventional AFM tool may not meet the requirement for testing the product in advanced technology node due to its large probe tip contact area and tilted contact angle. The tool's throughput and probe tip cost are also affected by complicated tip replacement mechanism and high adapter cost. Accordingly, solutions to these problems have been long sought but thus far have eluded those skilled in the art.